A continuum model for elasticity in a non-equilibrium multiphase system was introduced. It included smooth and singular strains, as well as their coupling to free surfaces, and was applied to the dynamics of misfitting hetero-epitaxial films. Above a critical thickness, defects relieved strain and competed with an interface instability. Depending upon their mobility, the defects could screen stresses by building up at large-curvature groove tips. This led to high ductility. However, they could be out-run by the tips; thus leading to brittleness. Hence, a non-equilibrium brittle-ductile transition resulted.

Dynamics of Dislocations and Surface Instabilities in Misfitting Heteroepitaxial Films. M.Haataja, J.Müller, A.D.Rutenberg, M.Grant: Physical Review B, 2002, 65[3], 035401 (5pp)